We have found, in preliminary experiments, that modest modifications of a chick's visual experience can cause severe axial myopia. Specifically restricting vision to the frontal visual field causes up to 24 diopters of myopia and a mean increase of 14% in the axial length of the eye, whereas restricting vision to the lateral field has no effect. We know of no other instance of specific visual experience producing extreme myopia. We have characterized the developmental course of the myopia, and we plan to study more fully the morphological changes in the eye (axial length, spacing of the refractive elements, curvature of lens and cornea) as this myopic conditions develops, in order to discover what changes occur first. We have found that the animals can recover from myopia, and, since we presume that this does not involve a decrease in axial length we are interested in what morphological changes are associated with this recovery. Finally we are particularly interested in what aspect of the altered visual experience is responsible for the development of the experimental myopia.